Metallic cans used as packaging for beer, soft drinks, and other liquid products are frequently provided with a can lid which includes an "easy-open" feature. This feature frequently consists of a scored or weakened segment to which a tab is affixed. To open the can, it is only necessary to lift the tab thereby causing the scoring to break and the scored segment of the can end to be depressed into the can. One source of consumer dissatisfaction occurs when activation of the tab results in the scored segment of the can lid being imperfectly opened. Another source of consumer dissatisfaction occurs when activation of the tab results in separation of the tab from the scored segment leaving the can unopened.
Since millions of cans incorporating this type of easy-open feature are utilized every day, it is necessary that some procedures be followed to ensure consistent quality of the can lids. One method randomly selects a statistically significant number of manufactured can lids which are then manually tested by employees. Such a procedure is generally undesirable because not only is it labor intensive but it also is extremely tiring for the employees involved and may result in injuries, such as strains of the finger or cuts from the can lids.
Many attempts have been made to mechanize the lid opening testing procedure. Typical of these are the devices and procedures disclosed by U.S. Pat. No. 3,318,143 (Helms), U.S. Pat. No. 3,464,261 (Helms), U.S. Pat. No. 3,559,471 (Schaffer), and U.S. Pat. No. 4,637,260 (Gilliam, et al.). None of these prior inventions, however, offer the features of a simple device which can rapidly test a large number of lids and duplicate the motion which is actually employed by a consumer when operating the easy-open feature. The devices disclosed in U.S. Pat. No. 3,318,143 (Helms), U.S. Pat. No. 3,464,261 (Helms), and U.S. Pat. No. 3,559,471 (Schaffer) are each single shot testing devices in which a lid is manually loaded into the machine. A linear force is then applied to the easy-open device to test the opening mechanism. Only U.S. Pat. No. 4,637,260 (Gilliam, et al.) provides a machine which automatically tests a plurality of lids. However, it is a complex machine employing a multiplicity of drive cylinders and sensing devices. Neither the device of Gilliam nor any of the other devices duplicates the rotating action actually employed by the consumer when operating the easy-open feature. Rather each tests the easy-open feature by applying an essentially linear force to the tab.
It is therefore among the objects of the present invention to provide a simple device which will test the easy-open feature of a plurality of can lids in a manner consistent with the actual use of the consumer. It is another object of the present invention to provide a device which will test a plurality of can lids in a consistent, repeatable manner. It is a further object of the present invention to provide a device which will automatically test a plurality of can lids without significant manual manipulation. Other objects and features will be in part apparent and in part pointed out hereinafter.